JPH0298662A - Ion extracting and analyzing apparatus - Google Patents

Abstract

PURPOSE:To effectively extract ions by moving an ion-contg. liquid in the form of holding the liquid in place between gas and an electrode to splash the liquid and extracting the ions by an electric field for extraction. CONSTITUTION:The effluent liquid fed from a column 5 is introduced through a pipe 17e of a nozzle part 6 of an ion extraction device 6' to the spacing between the needle-like electrode 16 and a 1st pipe 19 and is fed into the tip of the electrode 16 by a sample-feed gas while the liquid is exposed to the contact with the sample-feed gas supplied through the spacing between the 1st pipe 19 and a 2nd pipe 20. A high voltage is impressed from a power source 7 to the electrode 16 and the electric field is formed between the electrode 16 and the 1st ion extracting electrode 8. The ions in the effluent liquid are jumped as very small liquid droplets out of the tip of the electrode 16 by this electric field coupled with the feeding force of the sample-feed gas and the electrostatic force between the electrode 16 and the electrode 8. Further, the ions are extracted from the very small liquid droplets by rupturing the liquid surface layers thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ion extraction and analysis device, and in particular to a device suitable for extracting and analyzing ions in the effluent from a separation column.

[Conventional technology]

When a liquid containing ions flows out of a thin tube to which a high voltage is applied, the liquid becomes conical, and charged droplets are ejected from the tip in a well-directed manner. The phenomenon in which ions in a liquid are drawn out as droplets from the liquid by an electric field and atomized is called E HD (Electrohydro dynalysis).
mic ionization).

According to this method, there is no need to particularly heat the liquid during spraying, so even thermally unstable substances known as polar molecules, such as amino acids that make up proteins and nucleic acids that make up genes, can undergo thermal decomposition. Never.

In the case of this technology, it is possible to spray liquid at a rate of several μQ/win. However, the maximum allowable flow rate is too low to employ this technique as an ion extraction device for performing mass spectrometry of ions in the effluent coming out of a separation column of a liquid chromatograph. Therefore, a semi-micro column (~1
00 m Q/! 1 inch) or backed column (100
For μQ/l1ljn ~), the effluent was divided into 1. / 1
00 or l/1000]. However, such a split is not easy;
Moreover, the sensitivity of the entire system will be significantly impaired.

An improved method of ET-(D ionization has been proposed. It is published in Analytical Chemistry, Vol. 59, No. 2
No. 2, November 15, 1987, No. 2642-2646
Page (Analytical Chemistry.

VOQ, 59. N(122, November 5
．． L 987゜pP2642-264-6).

According to this, a fused silica capillary with an inner diameter of 50 μm is inserted into a stainless steel capillary with an inner diameter of 0.2 m. This is further inserted into a Teflon tube with an internal diameter of 0.8 m. Dry nitrogen at 2.5 atmospheres and 216 m/see is flowed between the stainless steel capillary and the Teflon tube. 3KV for stainless steel capillary,
Confront this? 1! A voltage of 600 μ is applied to the pole. This allows the fused silica capillary to contain several tens of μQ.
It has been reported that when a liquid of /sin flows through the capillary, a smoke-like mist of minute particles is generated.8 [Problem to be solved by the invention] In this technology, nitrogen gas is used to stabilize the liquid cone.

It is thought that this contributes to the miniaturization of droplets due to collision with droplets, and this is thought to be the main cause of the increase in flow rate.

However, according to experiments, even with this technology, 100μQ
It has been difficult to stably spray a liquid at a flow rate of /sin or more and extract ions. For this reason, this technique is still insufficient for use in backed columns (100 μΩ/win or more), which are often used in liquid chromatographs.

An object of the present invention is to provide an ion extraction and analysis device that can effectively extract ions.

[Means to solve the problem]

The ion extraction device of the present invention includes an electrode, a means for introducing a liquid containing ions to the surface of the electrode, a means for supplying a gas so as to move the liquid in a manner sandwiching it between the electrode, and the electrode. and means for generating an electric field for extracting ions.

The ion analyzer of the present invention has 5 electrodes to which a liquid containing ions is introduced, a means for supplying gas so that the liquid is moved between the electrodes, and a means for extracting the ions. and means for detecting the extracted ions.

[Effect]

The ion-containing liquid guided to the electrode surface is moved by the gas between the gas and the electrode, and the ions therein are ejected into space in the form of minute droplets by the ion extraction electric field. Furthermore, it is extracted from the minute droplets by breaking through the liquid surface layer.

Since the liquid is moved by the gas while being sandwiched between the gas and the electrode, vaporization of the liquid by the gas is promoted. In addition, since the moving speed of the surface of the liquid in contact with the gas is greater than the moving speed of the surface in contact with the electrode, the liquid is turned into droplets on the surface of the liquid in contact with the gas, and droplets are generated. promoted.

In this way, the gas accelerates the vaporization of the liquid, and the difference in moving speed between the two surfaces of the liquid causes the liquid to become droplets.

By promoting droplet formation, ions can be extracted effectively.

In addition, when applying a voltage to the electrode to form an electric field for ion extraction, ions of the same polarity as the electrode, that is, ions to be extracted, are placed in the liquid surface layer in contact with the electrode. There is a strong tendency for opposite charges to gather. For this reason, the resulting droplets contain many ions, which, combined with the Coulomb repulsion between ions, further promotes the vaporization of ions, that is, the extraction of ions.

〔Example〕

Referring to FIG. 1, the eluent stored in an eluent storage tank 1 is sent to a separation column 5 by a pump 2 through a damper 3 and a sample injection port 4. The damper 3 is used to suppress the pulsating flow of the eluent caused by the pump 2.

The sample is added or injected into the column 5 through the sample inlet 4 and is separated in the process of being sent through the column 5 with an eluent. The effluent from column 5 is sent to ion extraction device 6'.

The nozzle section 6 of the ion extraction device 6' is attached to the device wall 6b with a nut 6a, details of which are shown in Figure 2 (a).
), (b) and (Q). Referring to the figure, a linear or needle-shaped mold wA16 passes through tees 17 and 18 and is attached to tee 17 by a nut 17a via an airtight seal 17b. The needle electrode 16 is preferably made of a stable material such as Pt, Au, or C to prevent electrolysis. An insulating knob 15 is attached to one end of the needle electrode 16, and the other end is sharp. A first tube 19 is arranged around the needle electrode 16 and is attached to the tees 17 and 18 via airtight seals 17d and 18b by means of oaks h 17 c and 18a. A second tube 2o is arranged around the first tube 19, and the second tube is attached to the tee 18 by a nut 18c via an airtight seal 18d. A tube 17e communicating with the gap between the needle electrode 16 and the first tube 19 is attached to the tee 17 via an airtight seal 17g with a nut 171'.

Pipe 17e is connected to the lower end of column 5. A pipe 18e communicating with the gap between the first pipe 19 and the second pipe 20 is attached to the tee 18 via a hermetic seal 18g with a nut 18f, and the pipe 18e is connected to a gas source 30. A high voltage is applied to the needle electrode 16 by an electric current g7, and the tips of the linear electrode 16 protrude from the tip surfaces of the first and second tubes 9 and 20,
Is this protrusion amount (length) needle-like by loosening the nut 17a? !
! It can be adjusted by moving the pole 16 forward or backward.

The effluent from the column 5 that is sent to the ion extraction device 6' is led to the gap between the needle electrode 16 and the first tube 19 through the tube 17e. After passing through the gap between the needle electrode 19 and the first tube 19, the effluent is supplied from the gas supply device 30 through the gap between the tube 18e and the first and second tubes 19 and 200. While being exposed to contact with the sample feeding gas, the sample is fed to the tip of the needle electrode 16 by the sample feeding gas. The gas supply device 30 is capable of adjusting the amount of gas supplied. As the sample delivery gas, an inert gas such as argon or neon, or a gas such as nitrogen or nitrogen may be used.

A high voltage is applied to the needle electrode] 6 from the ffi source 7, thereby extracting ions between the needle electrode 16 and the first ion extraction electrode 8 at ground potential from the former toward the latter. An electric field is formed for this purpose. Therefore, if the effluent contains ions, the feeding force of the sample feeding gas and the electrostatic force between the needle electrode 16 and the first ion extraction electrode 8 combine to cause the ions in the effluent to be transferred to the needle electrode 1.
A micro droplet is ejected from the tip of the droplet against the surface tension of the liquid at the tip, and ions are further extracted from the surface of the droplet. The ions extracted in this way pass through the small hole in the first extraction electrode 9 and further through the small hole in the second ion extraction electrode 10 which is at ground potential. The ions passing through the small hole of the second ion extraction electrode 9 are transferred to the ion extraction electrode 10.
The mass is further drawn out to the quadruple bridge type H vessel 11 by
The mass separator selects only ions of the desired mass number, and the selected ions are detected by detector 12.

The mass separator 11 can also sequentially select ions of various mass numbers by mass number sweeping. Ions selected one after another in this way are detected one after another by the detector 12. The detection power signal of the detector 12 is amplified by an amplifier 13 and guided to a data processing device 14. Note that the mass separator 11 may be of a magnetic type.

A fan (not shown) is provided in the space between the needle electrode 16 and the first extraction electrode 8 to exhaust gas remaining in this space.
ventilated using Extraction electrode 10, mass separator 11
The detector 12 is placed in a space that is evacuated to a predetermined degree of vacuum by a vacuum pump (not shown). Further, the space between the first and second ion extraction electrodes 9 and 10 is also evacuated to a predetermined degree of vacuum by a vacuum pump (not shown).

As mentioned above, the effluent is transferred to the needle electrode 16 and the first extraction t.
After passing through the gap with the t-pole 8, it is exposed to contact with the sample feeding gas while being sent to the tip of the needle electrode 16.

Therefore, the vaporization of the solvent in the effluent is promoted, and the ion concentration increases.

When the effluent passes through the gap between the needle electrode 16 and the first extraction electrode 8 and is forcibly sent to the tip of the needle electrode 16 by the sample feeding gas, the flow velocity of the effluent on the liquid surface side vz The flow velocity v3 on the surface side of the linear electrode is slower than that. This is because there is friction between the effluent and the surface of the linear electrode 16.

As shown in FIGS. 3 and 4, vz>vs
If so, vaporization and droplet formation of the liquid on the liquid surface will be promoted,
Droplets are generated. At this time, ions similar to those of the needle electrode 16 are collected in the surface layer of the effluent, and opposite charges are collected near the surface of the needle electrode 16. Therefore, the droplet contains many ions, and together with the Coulomb repulsion between the ions, the vaporization of the ions is promoted.9Of course, the opposite charge that collects near the surface of the needle electrode 16 Lost at the electrode surface. In addition, in Fig. 4,
Vl is the flow rate of the sample feeding gas.

In this way, even if a relatively large amount of effluent is introduced into the ion extraction device 6', its ionization can be effectively and stably performed.

FIG. 5 is a diagram showing the relationship between the amount of effluent flowing into the sample ionization device 6' and the ion current value. The conditions for obtaining this data are as follows.

The diameter of the needle electrode 16 is 100 tt m (0, 1 m
)in.

The tip was sharpened by electrolytic polishing so that the radius was several μm and 8 degrees. Dry nitrogen gas was used as the sample feed gas, and its flow rate was set at IQ/min. Figure 2 (
As shown in c), the protrusion amount of the tip of the needle electrode 16 is 51Il11, and the outer diameter and inner diameter of the first tube 19 are 1 m and 0.25 m, respectively.

The outer diameter and inner diameter of the second tube 20 are respectively 4I [111
and 2Ilf11. The voltage applied to the needle electrode 16 was +3 KV.

In Fig. 5, A is the data when the needle-like ViA16 is present, and B is the data when the needle-like flHJj16 is not present. It can be seen that ionization is performed stably and effectively even in the case of . - On the other hand, when the needle electrode 16 is not present, the maximum flow rate is several tens of millimeters. From the above, the presence of the needle electrode 16 makes it possible to achieve stable and effective ionization even with a relatively large amount of effluent liquid.

FIG. 6 shows the ion current measurement system used to obtain the data shown in FIG. A is the case where the needle-like electrode is present, and B is the case where the needle-like electrode is not present. 8' is extraction 1
12' is an ion detector, 13' is an amplifier, and 30 is an ammeter.

FIG. 7 shows the protrusion ff1 of the needle electrode 16 from the first tube 19.
The relationship between ion current value and (length) is shown.

This data was obtained using the system shown in FIG. This data shows that there is almost no effect when the amount of protrusion is zero. The same applies when the amount of protrusion is too large.

The tip of the needle electrode 16 may be sharply pointed, or may be flat as shown in FIGS. 8 and 10, or round as shown in FIG. Electrode 16. The cross section of the first pipe 19 and the second pipe 20 is
It may be circular as shown in the figure and FIG. 9, or it may be rectangular as shown in FIG.

Depending on the sample solution, heating may be allowed to a certain extent.6 Heating can further increase the efficiency of vaporizing the solvent and therefore further enhance the effect of ion extraction. 11 and 12 are for this purpose. In FIG. 11, the entire nozzle portion 6 is surrounded by a heat block 21, which is heated by a cartridge heater 23. In FIG. In addition, FIG. 12 shows that the atomized components are transferred to the cartridge heater 2.
3. Vaporization is carried out through a hollow heat block 23 built in.

Note that 22 is a thermocouple for temperature measurement.

〔Effect of the invention〕

According to the present invention, an ion extraction and analysis device that can effectively extract ions is provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view partially shown in block form of an ion analyzer showing an embodiment of the present invention, FIG. 2(a) is an enlarged sectional view of the ion extraction section of FIG. b) is shown in Figure 2 (
Figure 2(c) is an enlarged sectional view of the tip of the needle-shaped electrode in Figure 2(a), Figure 3 is the right side view of the needle-shaped electrode in Figure 2(a), and Figure 3 is the right side view of the needle-shaped electrode in Figure 2(a). A further enlarged cross-sectional view of the tip, FIG. 4 is an explanatory diagram of the liquid splash effect, FIG. 5 is a diagram showing the relationship between the ion current value and the amount of outflowing liquid, and FIG. 6 is a configuration diagram of the ion current measurement system. FIG. 7 is a diagram showing the relationship between the ion current value and the amount of protrusion of the needle electrode, FIG. 8(a) is an enlarged sectional view of the tip of the nozzle part of another embodiment, and FIG. a
), FIG. 9(a) is an enlarged sectional view of the nozzle tip of yet another embodiment, and FIG. 9(b) is a right side view of FIG. 9(a).
), FIG. 10(a) is an enlarged sectional view of the nozzle tip of yet another embodiment, FIG. 10(b) is a right side view of FIG. 10(a), and FIG. 10(b) is a right side view of FIG. FIG. 11 is a sectional view of one embodiment of the heating device, and FIG. 12 is a sectional view of another embodiment of the heating device. DESCRIPTION OF SYMBOLS 1... Eluent storage tank, 2... Pump, 5... Column, 6... Nozzle section, 6'... Ion extraction device, 7...
·power supply. 11... Mass separator, 12... Detector, 16...
needle electrode, 19... first tube, 20... second tube,
21...Heat block, 22...Thermocouple, 23.
··heater.

Claims (1)

[Claims] 1. An electrode, means for introducing a liquid containing ions to the surface of the electrode, means for supplying a gas so that the liquid is moved between the electrodes, and the ions. An ion extraction device comprising means for generating an electric field so as to extract the ions. 2. An electrode, a means for introducing a liquid containing ions to the surface of the electrode, a means for supplying gas so as to move the liquid between the electrodes, and a voltage for extracting the ions. an ion extraction device, comprising: means for applying the above electrode to the electrode. 3. An electrode, means for introducing a liquid containing ions to the surface of the electrode, means for supplying gas so that the liquid is sandwiched between the electrodes, and means for generating an electric field to extract the ions. and the gas supply means includes means for setting the flow rate of the gas such that the moving speed of the surface of the liquid in contact with the gas is greater than that of the surface of the liquid in contact with the electrode surface. Ion extraction device. 4. A needle electrode, a first tube arranged to form a first gap around the needle electrode, and a first tube arranged to form a second gap around the first tube. a second pipe, a means for introducing a liquid containing ions into the first gap, a means for supplying gas to the second gap, and an ion extraction electrode disposed opposite to the needle-like electrode; means for forming an electric field between the needle-like electrode and the extraction electrode to extract the ions, the means for forming an electric field between the gas and the needle-like electrode after the liquid has passed through the first gap; An ion extraction device characterized in that the needle-shaped electrode protrudes from the first tube so as to be moved between the needles. 5. A needle electrode, a first tube arranged to form a first gap around the needle electrode, and a second tube arranged to form a second gap around the first tube. means for introducing a liquid containing ions into the first gap, means for supplying gas to the second gap, and an ion extraction electrode disposed opposite to the needle electrode. and means for applying a voltage to the needle-like electrode to form an electric field between the needle-like electrode and the extraction electrode to extract the ions, the needle-like electrode being arranged so that the liquid is in the first state. The gas supply means protrudes from the first tube so as to be moved between the gas and the needle electrode after passing through the gap, and the gas supply means is configured to control the movement of the surface of the liquid in contact with the gas. An ion extraction device comprising means for setting the flow velocity of the gas so that the velocity is higher than that of the surface of the needle-like electrode. 6. The ion extraction device according to claim 4 or 5, further comprising means for adjusting the length of the needle electrode protruding from the first tube. 7. Claims 1 and 2 further comprising means for heating the liquid.
, 3 or 6. 8. A needle electrode and a first electrode around which ions should be guided.
A first pipe arranged so that a gap is formed, and a second pipe arranged so that a second gap is formed around the first pipe to which gas is to be supplied. An ion extraction electrode device, wherein the needle-like electrode protrudes from the first tube. 9. The ion extraction electrode device according to claim 8, wherein the amount of protrusion of the needle electrode from the first tube is adjustable. 10, an electrode to which a liquid containing ions is guided;
A means for supplying a gas to move the liquid between the electrodes, a means for generating an electric field to extract the ions, and a means for detecting the extracted ions. Ion analyzer. 11. An electrode to the surface of which a liquid containing ions is guided;
means for supplying a gas so as to move the liquid between the electrodes; means for generating an electric field to extract the ions; means for mass-separating the extracted ions; An ion analyzer comprising means for detecting mass-separated ions. 12. A column for separating a sample liquid containing added ions by flowing an eluent, a means for extracting ions in the effluent from the column, and a means for detecting the extracted ions. The ion extraction means includes an electrode on the surface of which the effluent is guided, a means for supplying a gas so that the effluent is moved between the electrodes, and a means for supplying a gas between the gas and the electrode. an ion analyzer comprising means for generating an electric field so as to extract ions in the effluent that moves while being sandwiched therebetween. 13. A column for separating a sample liquid containing added ions by flowing an eluent, means for extracting ions in the effluent from the column, and means for mass-separating the extracted ions. , means for detecting the mass-separated ions, and the ion extraction means includes an electrode on the surface of which the effluent is introduced, and a gas such that the effluent is moved between the electrodes. and means for generating an electric field so as to extract ions in the effluent that moves while being sandwiched between the gas and the electrode.